re: Can you suggest any cake decoration store in San Francisco?

Pinar I am not sure of the status of this shop. I read that it may be closing, but you might give them a call when you are here. He does teach and makes wonderful cakes but I see there is also a supply shop. It couldn’t hurt to try.
http://bakingarts.net/store.html
He was in San Francisco but I see the address is now San Mateo. Not far from San Francisco if you are renting a car or have friends in the city who drive. Good luck.

Shirley